Fifty years ago, women in Asia were having, on average, more than five children each, and there was widespread fear of a "population explosion" in the region. Then birth rates began to fall--in several countries more steeply than anyone had anticipated. This unexpected trend has now raised concerns about the social and economic impact of extremely low fertility. Today, four of Asia's most prosperous economies--Japan, Singapore, South Korea, and Taiwan--have among the lowest birth rates in the world. With women having, on average, only one child each, these societies have expanding elderly populations and a shrinking workforce to pay for social services and drive economic growth. And in Japan, overall population numbers are already going down. Why are women choosing to have so few children? How are policymakers responding to these trends? Government leaders have initiated a variety of policies and programs designed to encourage marriage and childbearing, but to what effect? Given current social and economic trends, it is unlikely that Asia's steep fertility decline will be reversed, at least not in the foreseeable future.